Image encoding device and image processing device including the same

ABSTRACT

An image encoding device includes a first compression unit, a second compression unit, a third compression unit and an output unit. The first compression unit generates first compressed data by compressing first data associated with a reference block in an input image. The second compression unit generates second compressed data by compressing second data associated with a current compressing block in the input image when the current compressing block corresponds to a first pattern. The current compressing block is included in the reference block. The third compression unit generates third compressed data by compressing the second data when the current compressing block corresponds to one of a plurality of second patterns. The output unit outputs compressed data based on the first compressed data, the second compressed data and the third compressed data.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 2011-0128940, filed on Dec. 5, 2011 in the KoreanIntellectual Property Office (KIPO), the disclosure of which isincorporated by reference in its entirety herein.

TECHNICAL FIELD

Exemplary embodiments of the inventive concept relate generally toprocessing of image data to be displayed, and more particularly to animage encoding device and an image processing device including the imageencoding device.

DISCUSSION OF RELATED ART

A display system may include a display device to display images and animage processing device to improve a response speed of the displaydevice. For example, the image processing device may compensate theresponse speed of the display device based on a comparison of a previousimage frame with a current image frame. The display system may include astorage device for storing data of the previous image frame. However,when the quality of the image and size of the image displayed by thedisplay device are increased, so does the required capacity of thestorage device. Thus, there is a need for an image processing method andsystem that enables a storage device of a reduced capacity to be used ina display system.

SUMMARY

According to an exemplary embodiment of the inventive concept, an imageencoding device includes a first compression unit, a second compressionunit, a third compression unit and an output unit. The first compressionunit generates first compressed data by compressing first dataassociated with a reference block in an input image. The secondcompression unit generates second compressed data by compressing seconddata associated with a current compressing block in the input image whenthe current compressing block corresponds to a first pattern. Thecurrent compressing block is included in the reference block. The thirdcompression unit generates third compressed data by compressing thesecond data when the current compressing block corresponds to one of aplurality of second patterns. The output unit outputs compressed databased on the first compressed data, the second compressed data and thethird compressed data. The output compressed data may correspond to thecurrent compressing block.

The second compression unit may generate the second compressed data if adifference between a first pixel value of the second data and a secondpixel value of the second data is smaller than a threshold value. Thesecond compression unit may generate the second compressed data if adifference between a first pixel value and a second pixel value issmaller than a threshold value. The second data associated with thecurrent compressing block may include a plurality of pixel values. Eachof the first and second pixel values may be one of the plurality ofpixel values.

The third compression unit may generate the third compressed data if thedifference between the first pixel value and the second pixel value isequal to or larger than the threshold value.

The output unit may select one of the first compressed data, the secondcompressed data and the third compressed data as selected data, andoutput the compressed data based on the selected data. The selected datamay have a minimum error with respect to the second data.

The selected data may be one of the first compressed data and the secondcompressed data when the current compressing block corresponds to thefirst pattern. The selected data may be the third compressed data whenthe current compressing block corresponds to one of the plurality ofsecond patterns.

The first data may include a plurality of first pixel values and thesecond data may include a plurality of second pixel values. The firstcompression unit may include a first averaging block, a first modeselection block and a first compression block. The first averaging blockmay generate first average data by averaging the plurality of firstpixel values. The first mode selection block may generate a first modeselection signal by comparing the first average data with first previouscompressed data. The first mode selection signal may indicate acompression scheme for the first average data. The first previouscompressed data may be generated by compressing third data associatedwith a previous compressing block in the input image. The previouscompressing block may be adjacent the current compressing block. Thefirst compression block may generate the first compressed data bycompressing the first average data based on the first mode selectionsignal.

The first compressed data may be generated based on a differential pulsecode modulation (DPCM) scheme that calculates a difference between thefirst average data and the first previous compressed data and compressesthe first average data based on the calculated difference if the firstmode selection signal has a first logic level. The first compressed datamay be generated based on a pulse code modulation (PCM) scheme thattruncates a portion of the first average data if the first modeselection signal has a second logic level.

The second compression unit may include a second averaging block, asecond mode selection block and a second compression block. The secondaveraging block may generate second average data by averaging theplurality of second pixel values. The second mode selection block maygenerate a second mode selection signal by comparing the second averagedata with the first previous compressed data. The second mode selectionsignal may indicate a compression scheme for the second average data.The second compression block may generate the second compressed data bycompressing the second average data based on the second mode selectionsignal.

The third compression unit may include a third averaging block, a thirdmode selection block and a third compression block. The third averagingblock may divide the plurality of second pixel values into a first groupand a second group, may generate third average data by averaging pixelvalues included in the first group, and may generate fourth average databy averaging pixel values included in the second group. The third modeselection block may generate a third mode selection signal by comparingthe third and fourth average data with second previous compressed data.The third mode selection signal may indicate a compression scheme forthe third and fourth average data. The second previous compressed datamay be generated by compressing the third data in a manner distinct fromthe first previous compressed data. The third compression block maygenerate the third compressed data by compressing the third and fourthaverage data based on the third mode selection signal.

The image encoding device may further include a storage unit. Thestorage unit may store one of the first compressed data, the secondcompressed data and the third compressed data, and may output the firstprevious compressed data and the second previous compressed data thatwere previously stored in the storage unit.

The image encoding device may further include a pattern decision unit.The pattern decision unit may compare a first pixel value with a secondpixel value to generate comparison results and may generate a patterndecision signal based on the comparison results. The second dataassociated with the current compressing block may include a plurality ofpixel values. Each of the first and second pixel values may be one ofthe plurality of pixel values. The pattern decision signal may indicatewhether the current compressing block corresponds to the first patternor one of the plurality of second patterns.

According to an exemplary embodiment of the inventive concept, an imageprocessing device includes an image encoding device, a storage device,an image decoding device and a dynamic capacitance compensation (DCC)circuit. The image encoding device generates a compressed current imageby compressing an original current image. The storage device stores thecompressed current image, and outputs a compressed previous image thatwas previously stored in the storage device. The compressed previousimage is generated by compressing an original previous image precedingthe original current image. The image decoding device generates areconstructed previous image by decompressing the compressed previousimage. The DCC circuit generates a compensation image based on theoriginal current image and the reconstructed previous image. The imageencoding device includes a first compression unit, a second compressionunit, a third compression unit and an output unit. The first compressionunit generates first compressed data by compressing first dataassociated with a first reference block in the original current image.The second compression unit generates second compressed data bycompressing second data associated with a first compressing block in theoriginal current image when the first compressing block corresponds to afirst pattern. The first compressing block is included in the firstreference block. The third compression unit generates third compresseddata by compressing the second data when the first compressing blockcorresponds to one of a plurality of second patterns. The output unitgenerates output compressed data based on the first compressed data, thesecond compressed data and the third compressed data. The outputcompressed data corresponds to the current compressing block andcorresponds to a portion of the compressed current image.

The image processing device may further include a DCC input controlcircuit. The DCC input control circuit may determine whether theoriginal current image is a still image or a moving image based on thereconstructed previous image and a reconstructed current image, and mayoutput one of the original current image and the reconstructed previousimage as a selected image based on a result of the determination. Thereconstructed current image may be generated by decompressing thecompressed current image. The DCC circuit may generate the compensationimage based on the original current image and the selected image.

The image decoding device may include a mode determination unit, adecompression unit and an image reconstruction unit. The modedetermination unit may generate a mode determination signal bydetermining a compression scheme for fourth compressed data associatedwith a second compressing block in the original previous image. Thesecond compressing block may correspond to the first compressing blockin the original current image. The decompression unit may generatedecompressed data by decompressing the fourth compressed data based onthe mode determination signal. The image reconstruction unit maygenerate the reconstructed previous image by reconstructing thedecompressed data.

The decompression unit may include a first decompression unit, a seconddecompression unit and a third decompression unit. The firstdecompression unit may generate the decompressed data based on a firstdecompression scheme when the fourth compressed data is generated bycompressing a plurality of first pixel values associated with a secondreference block in the original previous image. The second referenceblock may correspond to the first reference block in the originalcurrent image. The second compressing block may be included in thesecond reference block. The second decompression unit may generate thedecompressed data based on a second decompression scheme when the fourthcompressed data is generated by compressing a plurality of second pixelvalues associated with the second compressing block. The thirddecompression unit may generate the decompressed data based on a thirddecompression scheme when the fourth compressed data is generated bydividing the plurality of second pixel values into a first group and asecond group, by compressing pixel values included in the first group,and by compressing pixel values included in the second group.

According to an exemplary embodiment of the inventive concept, acompression system includes a first compression unit configured togenerate first compressed data by compressing first average data that isan average of pixel values of a part of an input image, a secondcompression unit configured to generate second compressed data bycompressing second average data that is an average of pixel values of asub-part within the part smaller than the part when the sub-part is onepattern, a third compression unit configured to generate thirdcompressed data by compressing third and fourth average data when thesub-part is a second other pattern, where the third average data is anaverage of some of the pixel values and the fourth average data is anaverage of the remaining pixel values, and an output unit configured tooutput compressed data by selecting one of the first, second, and thirdcompressed data.

The first compression unit may be configured to output an error signalbased on a difference between the sub-part and the first compresseddata. The second compression unit may be configured to output an errorsignal based on a difference between the sub-part and the secondcompressed data. The third compression unit may be configured to outputan error signal based on a difference between the sub-part and the thirdcompressed data.

In an embodiment, each compression unit compresses average data inputthereto based on a differential pulse code modulation (DPCM) scheme whenpreviously compressed data is available and based on a PCM schemeotherwise.

In an embodiment, when the sub-part is not the one pattern, the secondcompression unit disables compression within itself. In an embodiment,when the sub-part is not the other pattern, the third compression unitdisables compression within itself.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the inventive concept will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings.

FIG. 1 is a block diagram illustrating an image encoding deviceaccording to an exemplary embodiment of the inventive concept.

FIGS. 2 and 3 are diagrams illustrating a portion of an exemplary inputimage compressed by an image encoding device of FIG. 1.

FIG. 4 is a block diagram illustrating an exemplary embodiment of afirst compression unit included in the image encoding device of FIG. 1.

FIGS. 5 and 6 are diagrams for describing exemplary compression schemesperformed by the image encoding device of FIG. 1.

FIGS. 7A and 7B are diagrams for describing an exemplary operation ofthe first compression unit of FIG. 4.

FIGS. 8A, 8B, 8C, 8D, 8E, 8F, 8G, 8H and 9 are diagrams for describingan exemplary operation of a pattern decision unit included in the imageencoding device of FIG. 1.

FIG. 10 is a block diagram illustrating an exemplary embodiment of asecond compression unit included in the image encoding device of FIG. 1.

FIGS. 11A and 11B are diagrams for describing an exemplary operation ofthe second compression unit of FIG. 10.

FIG. 12 is a block diagram illustrating an exemplary embodiment of athird compression unit included in the image encoding device of FIG. 1.

FIGS. 13A and 13B are diagrams for describing an exemplary operation ofthe third compression unit of FIG. 12.

FIG. 14 is a block diagram illustrating an exemplary embodiment of anoutput unit included in the image encoding device of FIG. 1.

FIG. 15 is a block diagram illustrating an exemplary embodiment of astorage unit included in the image encoding device of FIG. 1.

FIG. 16 is a block diagram illustrating an image encoding deviceaccording to an exemplary embodiment of the inventive concept.

FIG. 17 is a flow chart illustrating a method of encoding an imageaccording to an exemplary embodiment of the inventive concept.

FIG. 18 is a flow chart illustrating an exemplary embodiment of stepS110 in FIG. 17.

FIG. 19 is a flow chart illustrating an exemplary embodiment of stepS120 in FIG. 17.

FIG. 20 is a flow chart illustrating an exemplary embodiment of stepS130 in FIG. 17.

FIG. 21 is a flow chart illustrating an exemplary embodiment of stepS140 in FIG. 17.

FIG. 22 is a flow chart illustrating a method of encoding an imageaccording to an exemplary embodiment of the inventive concept.

FIG. 23 is a flow chart illustrating an exemplary embodiment of stepS220 in FIG. 22.

FIG. 24 is a flow chart illustrating a method of encoding an imageaccording to an exemplary embodiment of the inventive concept.

FIG. 25 is a block diagram illustrating an image decoding deviceaccording to an exemplary embodiment of the inventive concept.

FIG. 26 is a flow chart illustrating a method of decoding a compressedimage according to an exemplary embodiment of the inventive concept.

FIG. 27 is a block diagram illustrating an image processing deviceaccording to an exemplary embodiment of the inventive concept.

FIG. 28 is a block diagram illustrating an exemplary embodiment of a DCCcircuit included in the image processing device of FIG. 27.

FIG. 29 is a block diagram illustrating an image processing deviceaccording to exemplary embodiment of the inventive concept.

FIG. 30 is a block diagram illustrating an exemplary embodiment of a DCCinput control circuit included in the image processing device of FIG.29.

FIG. 31 is a block diagram illustrating a display system according to anexemplary embodiment of the inventive concept.

DETAILED DESCRIPTION

Exemplary embodiments of the inventive concept will be described morefully with reference to the accompanying drawings. This inventiveconcept may, however, be embodied in many different forms and should notbe construed as limited to the exemplary embodiments set forth herein.Like reference numerals refer to like elements throughout thisapplication.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise.

FIG. 1 is a block diagram illustrating an image encoding deviceaccording to an exemplary embodiment of the inventive concept.

Referring to FIG. 1, an image encoding device 100 includes a firstcompression unit 120, a second compression unit 130, a third compressionunit 140 and an output unit 150. The image encoding device 100 mayfurther include an input buffer unit 110, a pattern decision unit 160and a storage unit 170.

In an embodiment, the input buffer unit 110 stores image data IIMG of aninput image. A display device (not illustrated), such as a liquidcrystal display (LCD) device, may receive image data in units of lines(e.g., rows), and the input buffer unit 110 may include a line memorythat stores the image data IIMG of the input image in units of lines.The line memory in the input buffer unit 110 may store the image dataIIMG of the input image in lines of a predetermined size, and may outputfirst data RIMG and second data CIMG. The first data RIMG may be some ofthe image data IIMG and may be associated with a reference block in theinput image. The second data CIMG may also be some of the image dataIIMG and may be associated with a current compressing block in the inputimage. Each of the reference block and the current compressing block maybe a small image area in the input image. For example, the referenceblock may be a small portion of the input image. In an embodiment, thereference block includes a plurality of first unit pixels, and thecurrent compressing block includes a plurality of second unit pixels.The current compressing block is included within the reference block.The first data RIMG may include a plurality of first pixel valuesassociated with the plurality of first unit pixels (e.g., from thereference block), and the second data CIMG may include a plurality ofsecond pixel values associated with the plurality of second unit pixels(e.g., from the compressing block). The input image may be compressed inunits of the current compressing block.

FIGS. 2 and 3 are diagrams illustrating an exemplary portion of an inputimage that can be compressed by the image encoding device of FIG. 1.

Referring to FIGS. 1 and 2, in an embodiment, the image encoding device100 compresses the image data IIMG of the input image in units of 2×2pixel blocks, where each block is comprised of four unit pixels. Forexample, in an embodiment, the current compressing block CAREA in theinput image is comprised of four unit pixels P0, P1, P2 and P3 that arearranged in a 2×2 square matrix formation. However, this is merely anexample, as the image encoding device 100 may compress the image dataIIMG in units of other sizes.

In an embodiment, the second data CIMG associated with the currentcompressing block CAREA includes the plurality of second pixel values(e.g., four pixel values). Each of the plurality of second pixel valuesmay be associated with a respective one of the unit pixels P0, P1, P2and P3. Each of the plurality of second pixel values may have a redcomponent value R, a green component value G and a blue component valueB. For example, the red component value R, the green component value Gand the blue component value B may be 8 bits of data, respectively. Asingle pixel value may be 24 bits of data (e.g., 8 bits is the redcomponent, another 8 bits is the blue component, and the remaining 8bits is the green component), and the second data CIMG associated withthe current compressing block CAREA may be 96 bits of data (e.g., eachdistinct 24 bits corresponds to a different one of four unit pixels of a2×2 pixel block).

In an embodiment, the current compressing block CAREA is located withinthe reference block RAREA. For example, the reference block RAREA in theinput image may be comprised of sixteen unit pixels that are arranged ina 4×4 square matrix formation, and the unit pixels P0, P1, P2 and P3 maybe shared by the reference block RAREA and the current compressing blockCAREA. The first data RIMG associated with the reference block RAREA mayinclude the plurality of first pixel values (e.g., sixteen pixelvalues).

In an embodiment, the image encoding device 100 compresses the seconddata CIMG associated with the current compressing block CAREA based onboth the first data RIMG associated with the reference block RAREA andthe second data CIMG. The compression performed by the image encodedevice 100 may reduce flicker noise on the display device.

Referring to FIGS. 1, 2 and 3, in an embodiment, the input buffer unit110 stores the image data IIMG of the input image in units of four linesSTLINE. In an embodiment, the input buffer 110 sequentially outputs thefirst data RIMG associated with the reference block RAREA and the seconddata CIMG associated with the current compressing block CAREA.

Third data associated with a previous compressing block PCAREA may beused for compressing the second data CIMG. In an embodiment, theprevious compressing block PCAREA is adjacent the current compressingblock CAREA. However, in alternate embodiments, the previous compressingblock PCAREA need not be adjacent the current compressing block CAREA.The previous compressing block PCAREA may be comprised of a plurality ofthird unit pixels, and the third data may include a plurality of thirdpixel values associated with the plurality of third unit pixels. Thenumber of the third unit pixels may be substantially the same as thenumber of the second unit pixels. For example, the previous compressingblock PCAREA may be a small image area in the input image that islocated above the current compressing block CAREA. For example, thecurrent compressing block CAREA may be comprised of unit pixels includedin first lines and the previous compressing block PCAREA may becomprised of unit pixels included in second lines that are above thefirst lines. Similarly to the current compressing block CAREA, theprevious compressing block PCAREA may be comprised of four unit pixelsthat are arranged in a 2×2 square matrix formation. Some unit pixels maybe shared by the reference block RAREA and the previous compressingblock PCAREA. Data corresponding to the previous compressing blockPCAREA may be stored in the storage unit 170.

Although FIGS. 2 and 3 illustrate the current compressing block CAREAincluding four unit pixels and the reference block RAREA includingsixteen unit pixels, the number of unit pixels included in the currentcompressing block and the reference block are not limited thereto. Forexample, the reference block RAREA may include more than sixteen pixelsor less than sixteen pixels. Although FIG. 3 illustrates the inputbuffer unit 110 storing the image data IIMG of the input image in unitsof four lines STLINE, the number of lines stored in the input bufferunit is not limited thereto. For example, the input buffer 110 couldstore the image data in units of less than four lines or units greaterthan four lines.

Referring back to FIG. 1, the first compression unit 120 generates firstcompressed data CDAT1 based on a first compression scheme. In anembodiment, the first compression scheme generates the first compresseddata CDAT1 by averaging and compressing the first data RIMG. The firstcompression scheme may be divided into a first sub-compression schemeand a second sub-compression scheme depending on whether first previouscompressed data PCDAT1 is directly used. The first previous compresseddata PCDAT1 may correspond to the previous compressing block PCAREA inFIG. 3. The first and second sub-compression schemes will be describedbelow with reference to FIGS. 5 and 6.

The second compression unit 130 generates second compressed data CDAT2based on a second compression scheme when the current compressing blockCAREA in FIG. 2 corresponds to a first pattern. The second compressionscheme may generate the second compressed data CDAT2 by averaging andcompressing the second data CIMG. The second compression scheme may bedivided into the first sub-compression scheme and the secondsub-compression scheme depending on whether the first previouscompressed data PCDAT1 is directly used.

The third compression unit 140 generates third compressed data CDAT3based on a third compression scheme when the current compressing blockCAREA in FIG. 2 corresponds to one of a plurality of second patterns.The third compression scheme may generate third compressed data CDAT3 bydividing the current compressing block CAREA into at least two groups,and by averaging and compressing data corresponding to each group. Thethird compression scheme may be divided into the first sub-compressionscheme and the second sub-compression scheme depending on whether secondprevious compressed data PCDAT2 is directly used. The second previouscompressed data PCDAT2 may correspond to the previous compressing blockPCAREA in FIG. 3, and may be different from the first previouscompressed data PCDAT1.

In an exemplary embodiment, if the plurality of second unit pixelsincluded in the current compressing block CAREA have the same orsubstantially the same pixel value (e.g., if a difference between onepixel value of the plurality of second pixel values and another pixelvalue of the plurality of second pixel values is smaller than athreshold value), the current compressing block CAREA corresponds to thefirst pattern. In another exemplary embodiment, if some of the pluralityof second pixel values are different from the others of the plurality ofsecond pixel values (e.g., if the difference between one pixel value ofthe plurality of second pixel values and another pixel value of theplurality of second pixel values is equal to or larger than thethreshold value), the current compressing block CAREA corresponds to oneof the plurality of second patterns. The first pattern and the pluralityof the second patterns will be described below in detail with referenceto FIGS. 8A, 8B, 8C, 8D, 8E, 8F, 8G and 8H.

The output unit 150 generates output compressed data OCDAT based on thefirst compressed data CDAT1, the second compressed data CDAT2 and thethird compressed data CDAT3. For example, in an embodiment, the outputunit 150 selects one of the first compressed data CDAT1, the secondcompressed data CDAT2 and the third compressed data CDAT3 as selecteddata, and outputs compressed data OCDAT based on the selected data. Theselected data may have a minimum error with respect to the second dataCIMG. For example, a difference between the second data CIMG and theselected data may be smaller than differences between the second dataCIMG and the unselected data. The output compressed data OCDAT may be adigital bit stream signal. The output unit 150 may provide the selecteddata to the storage unit 170.

In an embodiment, the pattern decision unit 160 determines whether thecurrent compressing block CAREA corresponds to the first pattern or oneof the plurality of second patterns. For example, in an embodiment, thepattern decision unit 160 compares one pixel value of the plurality ofsecond pixel values with another pixel value of the plurality of secondpixel values to generate comparison results, and generates a patterndecision signal PDS based on the comparison results. In an embodiment,the pattern decision signal PDS indicates whether the currentcompressing block CAREA corresponds to the first pattern or one of theplurality of second patterns. The pattern decision signal PDS may beprovided to the second compression unit 130 and the third compressionunit 140, and may be further provided to the first compression unit 120.As will be described below with reference to FIGS. 4, 10 and 12, each ofthe first, second and third compression units 120, 130 and 140 mayperform different operations depending on a value of the patterndecision signal PDS.

In an embodiment, the storage unit 170 stores the selected data (e.g.,one of the first, second and third compressed data CDAT1, CDAT2 andCDAT3), and outputs the first previous compressed data PCDAT1 and thesecond previous compressed data PCDAT2 that were previously stored inthe storage unit 170. The first previous compressed data PCDAT1 may beprovided to the first and second compression units 120 and 130. Thesecond previous compressed data PCDAT2 may be provided to the thirdcompression unit 140.

Information loss may occur when an original image is compressed by animage encoding device. The original image may not be exactly reproducedby an image decoding device or may be reproduced with distortion. Thequality of a reproduced image may decrease as the compression ratio ofthe image encoding device increases. Further, memory capacities andsizes of the image encoding device and the image decoding device may belimited.

The image encoding device 100 according to an exemplary embodiment ofthe inventive concept generates the first, second and third compresseddata CDAT1, CDAT2 and CDAT3 based on three distinct schemes, andgenerates the output compressed data OCDAT based on the first, secondand third compressed data CDAT1, CDAT2 and CDAT3. Thus, the imageencoding device 100 may compress the second data CIMG associated withthe current compressing block CAREA with a relatively high compressionratio. For example, a conventional image encoding device has acompression ratio of about 1:3, whereas the image encoding device 100according to at least one embodiment has a compression ratio of about1:5. The image encoding device 100 may have a relatively small size,reduced power consumption, and enhanced operation speed. Flicker noiseon a display in an image display system that includes the image encodingdevice 100 may be reduced.

Hereinafter, an image encoding device according to an exemplaryembodiment of the inventive concept will be explained in detail withreference to exemplary configurations of the reference block RAREAcorresponding to a 4×4 pixel block and the current compressing blockCAREA corresponding to a 2×2 pixel block. However, in alternateembodiments, the reference block RAREA and the current compressing blockCAREA may have different sizes or shapes (e.g., rectangle, circle, oval,cross, etc.). For example, when the reference block RAREA has arectangular shape it can have various configurations such as 4×6, 3×4,5×6, etc.

FIG. 4 is a block diagram illustrating an exemplary embodiment of afirst compression unit included in the image encoding device of FIG. 1.

Referring to FIG. 4, the first compression unit 120 includes a firstaveraging block 122, a first mode selection block 124 and a firstcompression block 126.

In an embodiment, the first averaging block 122 generates first averagedata ADAT1 by averaging the plurality of first pixel values included inthe first data RIMG. For example, the first average data ADAT1 may begenerated by averaging the red component values R that are included inthe sixteen pixel values associated with the reference block RAREA inFIG. 2, by averaging the green component values G that are included inthe sixteen pixel values associated with the reference block RAREA inFIG. 2, and by averaging the blue component values B that are includedin the sixteen pixel values associated with the reference block RAREA inFIG. 2. The first average data ADAT1 may be 24 bits of data thatincludes 8 bits of the averaged red component value, 8 bits of theaveraged green component value and 8 bits of the averaged blue componentvalue.

The first mode selection block 124 may generate a first mode selectionsignal MS1 by comparing the first average data ADAT1 with the firstprevious compressed data PCDAT1. The first mode selection signal MS1 mayindicate a compression scheme for the first average data ADAT1. Thefirst previous compressed data PCDAT1 may be generated by compressingthe plurality of third pixel values included in the third dataassociated with the previous compressing block PCAREA in FIG. 3.

In an exemplary embodiment, the first mode selection signal MS1indicates one of the first sub-compression scheme and the secondsub-compression scheme. For example, the first mode selection signal MS1can indicate whether the first or second sub-compression scheme is to beused on first average data ADAT1. The first sub-compression scheme maybe performed by directly using the first previous compressed dataPCDAT1, and may be referred to as a differential pulse code modulation(DPCM) scheme. The second sub-compression scheme may be performed byindirectly using the first previous compressed data PCDAT1, and may bereferred to as a pulse code modulation (PCM) scheme. For example, thefirst compressed data CDAT1 may be generated based on the DPCM scheme ifthe first mode selection signal MS1 has a first logic level, and may begenerated based on the PCM scheme if the first mode selection signal MS1has a second other logic level. In the DPCM scheme, the first compresseddata CDAT1 may be generated by calculating a difference between thefirst average data ADAT1 and the first previous compressed data PCDAT1and by compressing the first average data ADAT1 based on the calculateddifference. In the PCM scheme, the first compressed data CDAT1 may begenerated by truncating a portion of the first average data ADAT1. In anembodiment, the first previous compressed data PCDAT1 is supplieddirectly to the first compression block 126.

In an exemplary embodiment, if the first previous compressed data PCDAT1corresponds to a predetermined null value, it is determined that thefirst previous compressed data PCDAT1 does not exist. In this example,the comparison operation by the first mode selection block 124 may beomitted (e.g., the comparing of the first average data ADAT1 with theprevious compressed PCDAT1), and the first mode selection block 124 maygenerate the first mode selection signal MS1 indicating the PCM scheme(e.g., having the second logic level).

FIGS. 5 and 6 are diagrams for describing compression schemes performedby the image encoding device of FIG. 1. FIG. 5 illustrates the firstsub-compression scheme (e.g., the DPCM scheme), and FIG. 6 illustratesthe second sub-compression scheme (e.g., the PCM scheme).

Referring to FIG. 5, average data ADAT may be compressed based on thefirst sub-compression scheme if a difference between the average dataADAT and previous compressed data PCDAT is smaller than a thresholdvalue. In the first sub-compression scheme, the average data ADAT may becompressed by generating a flag bit based on upper bits of the averagedata ADAT and upper bits of the previous compressed data PCDAT, and byadding lower bits of the average data ADAT to the flag bit. For example,the previous compressed data PCDAT may be directly used in the firstsub-compression scheme. In a first sub-decompression schemecorresponding to the first sub-compression scheme, the data compressedby the first sub-compression scheme may be decompressed by obtaining theupper bits of the previous compressed data PCDAT based on the flag bitand by adding lower bits of the data compressed by the firstsub-compression scheme to the obtained upper bits of the previouscompressed data PCDAT.

For example, the average data ADAT may be “11000001” and the previouscompressed data PCDAT may be “11001111,” as illustrated in FIG. 5. If itis assumed that the threshold value is “1111,” the difference betweenthe average data ADAT and the previous compressed data PCDAT is “1110,”which is smaller than the threshold value. Thus, the average data ADATmay be compressed based on the first sub-compression scheme. In thefirst sub-compression scheme, the flag bit may be generated as “1,” andmay indicate that the upper four bits of the average data ADAT aresubstantially the same as the upper four bits of the previous compresseddata PCDAT. The lower four bits “0001” of the average data ADAT may beadded to the flag bit “1,” and the compressed data may be generated as“10001.” In the first sub-decompression scheme, the upper four bits“1100” of the previous compressed data PCDAT may be obtained based onthe flag bit “1.” The lower four bits “0001” of the compressed data maybe added to the upper four bits “1100” of the previous compressed dataPCDAT, and the decompressed data may be generated as “11000001.”

Referring to FIG. 6, the average data ADAT may be compressed based onthe second sub-compression scheme if the difference between the averagedata ADAT and previous compressed data PCDAT is equal to or larger thanthe threshold value. In the second sub-compression scheme, the averagedata ADAT may be compressed by truncating at least one bit (e.g., atleast one of lower bits) of the average data ADAT. For example, theprevious compressed data PCDAT may be indirectly used in the secondsub-compression scheme. In a second sub-decompression schemecorresponding to the second sub-compression scheme, the data compressedby the second sub-compression scheme may be decompressed by adding atleast one of several predetermined insertion bits to the compresseddata. Although the insertion bits are different from the truncated bits,an error between the insertion bits and the truncated bits may benegligible.

For example, the average data ADAT may be “10000111” and the previouscompressed data PCDAT may be “11001111,” as illustrated in FIG. 6. If itis assumed that the threshold value is “1111,” the difference betweenthe average data ADAT and the previous compressed data PCDAT is“1001000,” which is larger than the threshold value. Thus, the averagedata ADAT may be compressed based on the second sub-compression scheme.In the second sub-compression scheme, the lower two bits “11” of theaverage data ADAT may be truncated, and the compressed data may begenerated as “100001.” In the second sub-decompression scheme, thepredetermined insertion bits “10” may be added to the compressed data,and the decompressed data may be generated as “10000110.” The errorbetween the average data ADAT “10000111” and the decompressed data“10000110” may be negligible.

Although FIGS. 5 and 6 illustrate the average data ADAT as 8 bits ofdata, the first average data ADAT1 in FIG. 4 may be 24 bits of data thatincludes 8 bits of the averaged red component value, 8 bits of theaveraged green component value and 8 bits of the averaged blue componentvalue, and the first average data ADAT1 may be compressed with respectto the averaged red component value, the averaged green component valueand the averaged blue component value, respectively. Further, thethreshold value, the flag bit and the insertion bits are not limited to“1111,” “1” and “10,” as illustrated in FIGS. 5 and 6.

Referring back to FIG. 4, the first compression block 126 may generatethe first compressed data CDAT1 by compressing the first average dataADAT1 based on the first mode selection signal MS1. For example, thefirst compression block 126 may generate the first compressed data CDAT1by compressing the first average data ADAT1 based on the firstsub-compression scheme if the first mode selection signal MS1 has thefirst logic level. The first compression block 126 may generate thefirst compressed data CDAT1 by compressing the first average data ADAT1based on the second sub-compression scheme if the first mode selectionsignal MS1 has the second logic level.

Although not illustrated in FIG. 4, the first compression unit 120 mayfurther receive the pattern decision signal PDS generated from thepattern decision unit 160 in FIG. 1, and may be selectively enabledbased on the pattern decision signal PDS. For example, when the currentcompressing block CAREA in FIG. 2 corresponds to the first pattern(e.g., when the pattern decision signal PDS has a first value), thefirst compression unit 120 is enabled, performs averaging andcompression operations, and generates the first compressed data CDAT1that corresponds to the first data RIMG associated with the referenceblock RAREA in FIG. 2. When the current compressing block CAREA in FIG.2 corresponds to one of the plurality of second patterns (e.g., when thepattern decision signal PDS has one of a plurality of second values),the first compression unit 120 is disabled, does not perform averagingand compression operations, and generates the first compressed dataCDAT1 having the predetermined null value.

FIGS. 7A and 7B are diagrams for describing an exemplary operation ofthe first compression unit of FIG. 4. FIG. 7A illustrates an example ofa bit stream of the first compressed data CDAT1 generated based on thesecond sub-compression scheme (e.g., the PCM scheme). FIG. 7Billustrates an example of a bit stream of the first compressed dataCDAT1 generated based on the first sub-compression scheme (e.g., theDPCM scheme).

Referring to FIG. 7A, MD represents the compression scheme for the firstaverage data ADAT1, R_MSB represents a portion of the averaged redcomponent value included in the first average data ADAT1, G_MSBrepresents a portion of the averaged green component value included inthe first average data ADAT1, and B_MSB represents a portion of theaveraged blue component value included in the first average data ADAT1.As described above with reference to FIG. 6, the lower bits of theaveraged red component value, the lower bits of the averaged greencomponent value and the lower bits of the averaged blue component valuemay be truncated in the second sub-compression scheme. Thus, R_MSB maycorrespond to the upper bits of the averaged red component value, G_MSBmay correspond to the upper bits of the averaged green component value,and B_MSB may correspond to the upper bits of the averaged bluecomponent value.

In an exemplary embodiment, the first compressed data CDAT1 is 19 bitsof data. 1 bit of data may be assigned to MD. For example, if the firstcompressed data CDAT1 is generated by averaging and compressing thefirst data RIMG (e.g., based on the first compression scheme and basedon the second sub-compression scheme), MD may be set to “0.” 6 bits ofdata may be assigned to R_MSB, G_MSB and B_MSB, respectively. The firstcompressed data CDAT1 may assure the accuracy of the upper six bits ofthe averaged red component value, the upper six bits of the averagedgreen component value, and the upper six bits of the averaged bluecomponent value.

Referring to FIG. 7B, MD and SUB_MD represent the compression scheme forthe first average data ADAT1, FLAG_RGB represents flag bits of theaveraged red, green and blue component values. R_LSB represents aportion of the averaged red component value included in the firstaverage data ADAT1, G_LSB represents a portion of the averaged greencomponent value included in the first average data ADAT1, and B_MSBrepresents a portion of the averaged blue component value included inthe first average data ADAT1. As described above with reference to FIG.5, the lower bits of the averaged red component value, the lower bits ofthe averaged green component value and the lower bits of the averagedblue component value need not be truncated, and instead can be added tothe flag bits in the first sub-compression scheme. Thus, R_LSB maycorrespond to the lower bits of the averaged red component value, G_LSBmay correspond to the lower bits of the averaged green component value,and B_MSB may correspond to the lower bits of the averaged bluecomponent value.

In an exemplary embodiment, the first compressed data CDAT1 is 19 bitsof data. 2 bits of data may be assigned to MD and SUB_MD, respectively.For example, if the first compressed data CDAT1 is generated byaveraging and compressing the first data RIMG (e.g., based on the firstcompression scheme and based on the first sub-compression scheme), MDand SUB_MD may be set to “10” and “00,” respectively. 3 bits of data maybe assigned to FLAG_RGB. Each bit of FLAG_RGB may be set to “1” if theupper four bits of the first average data ADAT1 are substantially thesame as the upper four bits of the first previous compressed dataPCDAT1, and may be set to “0” if the upper three bits of the firstaverage data ADAT1 are substantially the same as the upper three bits ofthe first previous compressed data PCDAT1. For example, if the upperfour bits of the averaged red, green and blue component values in thefirst average data ADAT1 are substantially the same as the upper fourbits of averaged red, green and blue data in the first previouscompressed data PCDAT1, respectively, FLAG_RGB may be set to “111.” 4bits of data may be assigned to R_LSB, G_LSB and B_LSB, respectively.The first compressed data CDAT1 may assure the accuracy of the upperseven or eight bits of the averaged red component value, the upper sevenor eight bits of the averaged green component value, and the upper sevenor eight bits of the averaged blue component value depending on each bitof FLAG_RGB.

FIGS. 8A, 8B, 8C, 8D, 8E, 8F, 8G, 8H and 9 are diagrams for describingan exemplary operation of a pattern decision unit included in the imageencoding device of FIG. 1. FIG. 8A illustrates an example of the firstpattern. FIGS. 8B, 8C, 8D, 8E, 8F, 8G and 8H illustrate examples of theplurality of second patterns, respectively. FIG. 9 illustrates anexample of a reference table that can be used to determine whether apattern corresponds to the current compressing block CAREA in FIG. 2.

Referring to FIG. 8A, if the plurality of unit pixels P0, P1, P2 and P3included in the current compressing block CAREA have the same orsubstantially the same pixel value, the current compressing block CAREAcorresponds to the first pattern.

Referring to FIGS. 8B, 8C, 8D, 8E, 8F, 8G and 8H, if some of the pixelvalues associated with the unit pixels P0, P1, P2 and P3 are differentfrom the others of the pixel values associated with the unit pixels P0,P1, P2 and P3, the current compressing block CAREA corresponds to one ofthe plurality of second patterns.

In an embodiment, the number of the second patterns is seven if thecurrent compressing block CAREA is comprised of four unit pixels P0, P1,P2 and P3. For example, the second patterns may include a pattern Aillustrated in FIG. 8B, a pattern B illustrated in FIG. 8C, a pattern Cillustrated in FIG. 8D, a pattern D illustrated in FIG. 8E, a pattern Eillustrated in FIG. 8F, a pattern F illustrated in FIG. 8G, and apattern G illustrated in FIG. 8H. In the pattern A, a pixel valueassociated with the unit pixel P0 may be different from pixel valuesassociated with the unit pixels P1, P2 and P3. In the pattern B, thepixel value associated with the unit pixel P1 may be different from thepixel values associated with the unit pixels P0, P2 and P3. In thepattern C, the pixel value associated with the unit pixel P2 may bedifferent from the pixel values associated with the unit pixels P0, P1and P3. In the pattern D, the pixel value associated with the unit pixelP3 may be different from the pixel values associated with the unitpixels P0, P1 and P2. In the pattern E, the pixel values associated withthe unit pixels P0 and P1 may be different from the pixel valuesassociated with the unit pixels P2 and P3. In the pattern F, the pixelvalues associated with the unit pixels P0 and P2 may be different fromthe pixel values associated with the unit pixels P1 and P3. In thepattern G, the pixel values associated with the unit pixels P0 and P3may be different from the pixel values associated with the unit pixelsP1 and P2.

Referring to FIGS. 1 and 9, in an embodiment, the pattern decision unit160 generates a plurality of parameters PARA01, PARA23, PARA02, PARA13,PARA03 and PARA12 based on the pixel values associated with the unitpixels P0, P1, P2 and P3. The current compressing area CAREA may becomprised of the unit pixels P0, P1, P2 and P3, and the second data CIMGmay include four pixel values associated with the unit pixels P0, P1, P2and P3.

A first parameter PARA01 may correspond to a difference between thepixel value associated with the unit pixel P0 and the pixel valueassociated with the unit pixel P1. A second parameter PARA23 maycorrespond to a difference between the pixel value associated with theunit pixel P2 and the pixel value associated with the unit pixel P3. Athird parameter PARA02 may correspond to a difference between the pixelvalue associated with the unit pixel P0 and the pixel value associatedwith the unit pixel P2. A fourth parameter PARA13 may correspond to adifference between the pixel value associated with the unit pixel P1 andthe pixel value associated with the unit pixel P3. A fifth parameterPARA03 may correspond to a difference between the pixel value associatedwith the unit pixel P0 and the pixel value associated with the unitpixel P3. A sixth parameter PARA12 may correspond to a differencebetween the pixel value associated with the unit pixel P1 and the pixelvalue associated with the unit pixel P2.

The plurality of parameters PARA01, PARA23, PARA02, PARA13, PARA03 andPARA12 may be represented by Equations 1, 2, 3, 4, 5 and 6,respectively.PARA01=|R0−R1|+|G0−G1|+|B0−B1|  [Equation 1]PARA23=|R2−R3|+|G2−G3|+|B2−B3|  [Equation 2]PARA02=|R0−R2|+|G0−G2|+|B0−B2|  [Equation 3]PARA13=|R1−R3|+|G1−G3|+|B1−B3|  [Equation 4]PARA03=|R0−R3|+|G0−G3|+|B0−B3|  [Equation 5]PARA12=|R1−R2|+|G1−G2|+|B1−B2|  [Equation 6]

In the Equations 1, 2, 3, 4, 5 and 6, R0, G0 and B0 represent the red,green and blue component values of the pixel value associated with theunit pixel P0. R1, G1 and B1 represent the red, green and blue componentvalues of the pixel value associated with the unit pixel P1. R2, G2 andB2 represent the red, green and blue component values of the pixel valueassociated with the unit pixel P2. R3, G3 and B3 represent the red,green and blue component values of the pixel value associated with theunit pixel P3.

The pattern decision unit 160 may generate the pattern decision signalPDS based on the plurality of parameters PARA01, PARA23, PARA02, PARA13,PARA03 and PARA12 and the threshold value TH. The pattern decision unit160 may determine whether the current compressing block CAREAcorresponds to the first pattern or one of the plurality of secondpatterns, based on the reference table of FIG. 9. In FIG. 9, PAT1represents the first pattern in FIG. 8A, PAT2A represents the pattern Ain FIG. 8B, PAT2B represents the pattern B in FIG. 8C, PAT2C representsthe pattern C in FIG. 8D, PAT2D represents the pattern D in FIG. 8E,PAT2E represents the pattern E in FIG. 8F, PAT2F represents the patternF in FIG. 8G, and PAT2G represents the pattern G in FIG. 8H.

For example, if all of the plurality of parameters PARA01, PARA23,PARA02, PARA13, PARA03 and PARA12 are smaller than the threshold valueTH, it is determined that the current compressing block CAREAcorresponds to the first pattern in FIG. 8A. If the first, third andfifth parameters PARA01, PARA02 and PARA03 are larger than the thresholdvalue TH, and if the second, fourth and sixth parameters PARA23, PARA13and PARA12 are smaller than the threshold value TH, it is determinedthat the current compressing block CAREA corresponds to the pattern A inFIG. 8B.

In an exemplary embodiment, if the current compressing block CAREAcorresponds to the first pattern in FIG. 8A, the pattern decision signalPDS may be set to “000.” If the current compressing block CAREAcorresponds to the pattern A in FIG. 8B, the pattern decision signal PDSmay be set to “001.” If the current compressing block CAREA correspondsto the pattern B in FIG. 8C, the pattern decision signal PDS may be setto “010.” If the current compressing block CAREA corresponds to thepattern C in FIG. 8D, the pattern decision signal PDS may be set to“011.” If the current compressing block CAREA corresponds to the patternD in FIG. 8E, the pattern decision signal PDS may be set to “100.” Ifthe current compressing block CAREA corresponds to the pattern E in FIG.8F, the pattern decision signal PDS may be set to “101.” If the currentcompressing block CAREA corresponds to the pattern F in FIG. 8G, thepattern decision signal PDS may be set to “110.” If the currentcompressing block CAREA corresponds to the pattern G in FIG. 8H, thepattern decision signal PDS may be set to “111.” Thus, each bit patternof the pattern decision signal PDS corresponds to a different one of thepatterns.

Although not illustrated in FIG. 1, the pattern decision unit 160 mayinclude a parameter generation block and a pattern decision signalgeneration block. The parameter generation block may generate theplurality of parameters PARA01, PARA23, PARA02, PARA13, PARA03 andPARA12 based on the pixel values associated with the unit pixels P0, P1,P2 and P3. The pattern decision signal generation block may generate thepattern decision signal PDS based on the threshold value TH and theplurality of parameters PARA01, PARA23, PARA02, PARA13, PARA03 andPARA12.

FIG. 10 is a block diagram illustrating an exemplary embodiment of asecond compression unit included in the image encoding device of FIG. 1.

Referring to FIG. 10, the second compression unit 130 includes a secondaveraging block 132, a second mode selection block 134 and a secondcompression block 136.

The second averaging block 132 may generate second average data ADAT2 byaveraging the plurality of second pixel values included in the seconddata CIMG. For example, the second average data ADAT2 may be generatedby averaging the red component values R that are included in the fourpixel values associated with the current compressing block CAREA in FIG.2, by averaging the green component values G that are included in thefour pixel values associated with the current compressing block CAREA inFIG. 2, and by averaging the blue component values B that are includedin the four pixel values associated with the current compressing blockCAREA in FIG. 2. The second average data ADAT2 may be 24 bits of datathat includes 8 bits of the averaged red component value, 8 bits of theaveraged green component value and 8 bits of the averaged blue componentvalue.

The second mode selection block 134 may generate a second mode selectionsignal MS2 by comparing the second average data ADAT2 with the firstprevious compressed data PCDAT1. The second mode selection signal MS2may indicate a compression scheme for the second average data ADAT2. Inan exemplary embodiment, the second mode selection signal MS2 indicateone of the first sub-compression scheme that is described with referenceto FIG. 5 and the second sub-compression scheme that is described withreference to FIG. 6. In another exemplary embodiment, if the firstprevious compressed data PCDAT1 corresponds to the predetermined nullvalue, the second mode selection block 134 generates the second modeselection signal MS2 indicating the second sub-compression scheme.

The second compression block 136 may generate the second compressed dataCDAT2 by compressing the second average data ADAT2 based on the secondmode selection signal MS2.

The second averaging block 132 and the second compression block 136 mayfurther receive the pattern decision signal PDS, and may be selectivelyenabled based on the pattern decision signal PDS. For example, when thecurrent compressing block CAREA in FIG. 2 corresponds to the firstpattern (e.g., when the pattern decision signal PDS is “000”), thesecond averaging block 132 and the second compression block 136 areenabled, perform averaging and compression operations, and generate thesecond compressed data CDAT2 that corresponds to the second data CIMGassociated with the current compressing block CAREA in FIG. 2. When thecurrent compressing block CAREA in FIG. 2 corresponds to one of theplurality of second patterns (e.g., when the pattern decision signal PDSis one of “001,” “010,” “011,” “100,” “101,”, “110” and “111”), thesecond averaging block 132 and the second compression block 136 aredisabled, do not perform averaging and compression operations, andgenerate the second compressed data CDAT2 that has the predeterminednull value.

FIGS. 11A and 11B are diagrams for describing an exemplary operation ofthe second compression unit of FIG. 10. FIG. 11A illustrates an exampleof a bit stream of the second compressed data CDAT2 generated by thesecond sub-compression scheme (e.g., the PCM scheme). FIG. 11Billustrates an example of a bit stream of the second compressed dataCDAT2 generated by the first sub-compression scheme (e.g., the DPCMscheme).

Referring to FIG. 11A, MD and SUB_MD represent the compression schemefor the second average data ADAT2, R_MSB represents a portion of theaveraged red component value included in the second average data ADAT2,G_MSB represents a portion of the averaged green component valueincluded in the second average data ADAT2, and B_MSB represents aportion of the averaged blue component value included in the secondaverage data ADAT2. R_MSB may correspond to the upper bits of theaveraged red component value, G_MSB may correspond to the upper bits ofthe averaged green component value, and B_MSB may correspond to theupper bits of the averaged component value data.

In an exemplary embodiment, the second compressed data CDAT2 is 19 bitsof data. 2 bits of data may be assigned to MD and SUB_MD, respectively.For example, if the second compressed data CDAT2 is generated byaveraging and compressing the second data CIMG (e.g., based on thesecond compression scheme and on the second sub-compression scheme), MDand SUB_MD may be set to “10” and “01,” respectively. 5 bits of data maybe assigned to R_MSB, G_MSB and B_MSB, respectively. The secondcompressed data CDAT2 may assure the accuracy of the upper five bits ofthe averaged red component value, the upper five bits of the averagedgreen component value, and the upper five bits of the averaged bluecomponent value.

Referring to FIG. 11B, MD and SUB_MD represent the compression schemefor the second average data ADAT2 and FLAG_RGB represents flag bits ofthe averaged red, green and blue component values. R_LSB represents aportion of the averaged red component value in the second average dataADAT2, G_LSB represents a portion of the averaged green component valuein the second average data ADAT2, and B_MSB represents a portion of theaveraged blue component value in the second average data ADAT2. R_LSBmay correspond to the lower bits of the averaged red component value,G_LSB may correspond to the lower bits of the averaged green componentvalue, and B_LSB may correspond to the lower bits of the averaged bluecomponent value.

In an exemplary embodiment, the second compressed data CDAT2 is 19 bitsof data. 2 bits of data may be assigned to MD and SUB_MD, respectively.For example, if the second compressed data CDAT2 is generated byaveraging and compressing the second data CIMG (e.g., based on thesecond compression scheme and based on the first sub-compressionscheme), MD and SUB_MD may be set to “10” and “10,” respectively. 3 bitsof data may be assigned to FLAG_RGB. Each bit of FLAG_RGB may be set to“1” if the upper four bits of the second average data ADAT2 aresubstantially the same as the upper four bits of the first previouscompressed data PCDAT1, and may be set to “0” if the upper three bits ofthe second average data ADAT2 are substantially the same as the upperthree bits of the first previous compressed data PCDAT1. 4 bits of datamay be assigned to R_LSB, G_LSB and B_LSB, respectively. The secondcompressed data CDAT2 may assure the accuracy of upper seven or eightbits of the averaged red component value, upper seven or eight bits ofthe averaged green component value, and upper seven or eight bits of theaveraged blue component value depending on each bit of FLAG_RGB.

FIG. 12 is a block diagram illustrating an exemplary embodiment of athird compression unit included in the image encoding device of FIG. 1.

Referring to FIG. 12, the third compression unit 140 includes a thirdaveraging block 142, a third mode selection block 144 and a thirdcompression block 146.

In an embodiment, the third averaging block 142 divides the plurality ofsecond pixel values included in the second data CIMG into a first groupand a second group, generates third average data ADAT3 based on pixelvalues included in the first group, and generates fourth average dataADAT4 based on pixel values included in the second group. In anexemplary embodiment, each of the third and fourth average data ADAT3and ADAT4 is 24 bits of data that includes 8 bits of the averaged redcomponent value, 8 bits of the averaged green component value and 8 bitsof the averaged blue component value.

For example, when the current compressing block CAREA corresponds to thepattern A in FIG. 8B, the pixel value associated with the unit pixel P0may be determined as the first group, and the pixel values associatedwith the unit pixels P1, P2 and P3 may be determined as the secondgroup. The third averaging block 142 may output the pixel valueassociated with the unit pixel P0 as the third average data ADAT3, andmay generate the fourth average data ADAT4 by averaging the pixel valuesassociated with the unit pixels P1, P2 and P3. For example, when thecurrent compressing block CAREA corresponds to the pattern E in FIG. 8F,the pixel values associated with the unit pixels P0 and P1 may bedetermined as the first group, and the pixel values associated with theunit pixels P2 and P3 may be determined as the second group. The thirdaveraging block 142 may generate the third average data ADAT3 byaveraging the pixel values associated with the unit pixels P0 and P1,and may generate the fourth average data ADAT4 by averaging the pixelvalues associated with the unit pixels P2 and P3.

The third mode selection block 144 may generate a third mode selectionsignal MS3 by comparing the third and fourth average data ADAT3 andADAT4 with second previous compressed data PCDAT2. The third modeselection signal MS3 may indicate a compression scheme for the third andfourth average data ADAT3 and ADAT4. The second previous compressed dataPCDAT2 may be generated by compressing the third data associated withthe previous compressing block PCAREA in FIG. 3, in a manner distinctfrom the first previous compressed data PCDAT1. For example, the firstprevious compressed data PCDAT1 may be generated by compressing theplurality of third pixel values included in the third data based on thefirst compression scheme or the second compression scheme. The secondprevious compressed data PCDAT2 may be generated by compressing theplurality of third pixel values included in the third data based on thethird compression scheme.

In an exemplary embodiment, the third mode selection signal MS3indicates one of the first sub-compression scheme that is described withreference to FIG. 5 and the second sub-compression scheme that isdescribed with reference to FIG. 6. In another exemplary embodiment, ifthe second previous compressed data PCDAT2 corresponds to thepredetermined null value, the third mode selection block 144 generatesthe third mode selection signal MS3 indicating the secondsub-compression scheme.

The third compression block 146 may generate the third compressed dataCDAT3 by compressing the third and fourth average data ADAT3 and ADAT4based on the third mode selection signal MS3.

The third averaging block 142 and the third compression block 146 mayfurther receive the pattern decision signal PDS, and may be selectivelyenabled based on the pattern decision signal PDS. For example, when thecurrent compressing block CAREA in FIG. 2 corresponds to one of theplurality of second patterns (e.g., when the pattern decision signal PDSis one of “001,” “010,” “011,” “100,” “101,”, “110” and “111”), thethird averaging block 142 and the third compression block 146 areenabled, perform averaging and compression operations, and generate thethird compressed data CDAT3 that corresponds to the second data CIMGassociated with the current compressing block CAREA in FIG. 2. When thecurrent compressing block CAREA in FIG. 2 corresponds to the firstpattern (e.g., when the pattern decision signal PDS is “000”), the thirdaveraging block 142 and the third compression block 146 are disabled, donot perform averaging and compression operations, and generate the thirdcompressed data CDAT3 that has the predetermined null value.

FIGS. 13A and 13B are diagrams for describing an exemplary operation ofthe third compression block of FIG. 12. FIG. 13A illustrates an exampleof a bit stream of the third compressed data CDAT3 generated by thesecond sub-compression scheme (e.g., the PCM scheme). FIG. 13Billustrates an example of a bit stream of the third compressed dataCDAT3 generated by the first sub-compression scheme (e.g., the DPCMscheme).

Referring to FIG. 13A, MD and S represent the compression scheme for thethird and fourth average data ADAT3 and ADAT4, PAT represents a patterntype of the current compressing block CAREA, and NA represents unusedbits. RA represents a portion of the averaged red component valueincluded in the third average data ADAT3, GA represents a portion of theaveraged green data included in the third average data ADAT3, and BArepresents a portion of the averaged blue data included in the thirdaverage data ADAT3. RB represents a portion of the averaged red dataincluded in the fourth average data ADAT4, GB represents a portion ofthe averaged green data included in the fourth average data ADAT4, andBB represents a portion of the averaged blue data included in the fourthaverage data ADAT4. RA, GA and BA may correspond to the upper bits ofthe averaged red, green and blue component values included in the thirdaverage data ADAT3, respectively. RB, GB and BB may correspond to theupper bits of the averaged red, green and blue component values includedin the fourth average data ADAT4, respectively.

In an exemplary embodiment, the third compressed data CDAT3 is 19 bitsof data. 2 bits of data may be assigned to MD, and 1 bit of data may beassigned to S. For example, if the third compressed data CDAT3 isgenerated by dividing the current compressing block CAREA into twogroups and by averaging and compressing data corresponding to each group(e.g., based on the third compression scheme and based on the secondsub-compression scheme), MD and S may be set to “11” and “0,”respectively. 3 bits of data may be assigned to PAT. For example, if thecurrent compressing block CAREA corresponds to one of the patterns A, B,C, D, E, F and G, PAT may be set to one of “001,” “010,” “011,” “100,”“101,”, “110” and “111.” 1 bit of data may be assigned to NA, and 2 bitsof data may be assigned to RA, GA, BA, RB, GB and BB, respectively. Thethird compressed data CDAT3 may assure the accuracy of the upper twobits of the averaged red, green and blue component values included inthe third average data ADAT3 and the upper two bits of the averaged red,green and blue component values included in the fourth average dataADAT4.

Referring to FIG. 13B, MD and S represent the compression scheme for thethird and fourth average data ADAT3 and ADAT4. PAT and T represent apattern type of the current compressing block CAREA. RA, GA and BArepresent a portion of the averaged red, green and blue component valuesincluded in the third average data ADAT3, respectively. RB, GB and BBrepresent a portion of the averaged red, green and blue component valuesincluded in the fourth average data ADAT4, respectively. RA, GA and BAmay correspond to the lower bits of the averaged red, green and bluedata included in the third average component values ADAT3, respectively.RB, GB and BB may correspond to the lower bits of the averaged red,green and blue component values included in the fourth average dataADAT4, respectively.

In an exemplary embodiment, the third compressed data CDAT3 is 19 bitsof data. 2 bits of data may be assigned to MD, and 1 bit of data may beassigned to S. For example, if the third compressed data CDAT3 isgenerated by dividing the current compressing block CAREA into twogroups and by averaging and compressing data corresponding to each group(e.g., based on the third compression scheme and based on the firstsub-compression scheme), MD and S may be set to “11” and “1,”respectively. 3 bits of data may be assigned to PAT. For example, if thecurrent compressing block CAREA corresponds to one of the patterns A, B,C, D, E, F and G, PAT may be set to one of “001,” “010,” “011,” “100,”“101,”, “110” and “111.” 1 bit of data may be assigned to T. Forexample, if the second data CIMG associated with the current compressingblock CAREA is toggled with respect to the third data associated withthe previous compressing block PCAREA, T may be set to “1.” If thesecond data CIMG is not toggled with respect to the third data, T may beset to “0.” 2 bits of data may be assigned to RA, GA, BA, RB, GB and BB,respectively. The third compressed data CDAT3 may assure the accuracy ofthe upper four bits of the averaged red, green and blue component valuesincluded in the third average data ADAT3 and the upper four bits of theaveraged red, green and blue component values included in the fourthaverage data ADAT4.

FIG. 14 is a block diagram illustrating an exemplary embodiment of anoutput unit included in the image encoding device of FIG. 1.

Referring to FIG. 14, the output unit 150 includes an error calculationblock 152, a data selection block 154 and a bit stream generation block156.

The error calculation block 152 may generate a first error signal ES1, asecond error signal ES2 and a third error signal ES3 based on the firstcompressed data CDAT1, the second compressed data CDAT2, the thirdcompressed data CDAT3 and the second data CIMG. The first error signalES1 may correspond to a difference between the second data CIMG and thefirst compressed data CDAT1. The second error signal ES2 may correspondto a difference between the second data CIMG and the second compresseddata CDAT2. The third error signal ES3 may correspond to a differencebetween the second data CIMG and the third compressed data CDAT3.

In an exemplary embodiment, if the current compressing block CAREAcorresponds to the first pattern, the third compressed data CDAT3corresponds to the predetermined null value, and the third error signalES3 corresponding to the third compressed data CDAT3 has a maximum errorvalue. In another exemplary embodiment, if the current compressing blockCAREA corresponds to one of the plurality of second patterns, the secondcompressed data CDAT2 and/or the first compressed data CDAT1 correspondsto the predetermined null value, and the second error signal ES2corresponding to the second compressed data CDAT2 and/or the first errorsignal ES1 corresponding to the first compressed data CDAT1 have themaximum error value.

The data selection block 154 may select one of the first compressed dataCDAT1, the second compressed data CDAT2 and the third compressed dataCDAT3 as the selected data, based on the first error signal ES1, thesecond error signal ES2 and the third error signal ES3. The selecteddata may have a minimum error with respect to the second data CIMG, andmay be provided to the bit stream generation block 156 and the storageunit 170 in FIG. 1. The bit stream generation block 156 may generate theoutput compressed data OCDAT based on the selected data.

In an exemplary embodiment, the selected data may be one of the firstcompressed data CDAT1 and the second compressed data CDAT2 when thecurrent compressing block CAREA corresponds to the first pattern, andthe selected data may be the third compressed data CDAT3 when thecurrent compressing block CAREA corresponds to one of the plurality ofsecond patterns. In another exemplary embodiment, the selected data maybe one of the first compressed data CDAT1 and the second compressed dataCDAT2 when the current compressing block CAREA corresponds to the firstpattern, and the selected data may be one of the first compressed dataCDAT1 and the third compressed data CDAT3 when the current compressingblock CAREA corresponds to one of the plurality of second patterns.

FIG. 15 is a block diagram illustrating an exemplary embodiment of astorage unit included in the image encoding device of FIG. 1.

Referring to FIG. 15, the storage unit 170 includes a first storageblock 172 and a second storage block 174.

The first storage block 172 may store the selected data output from thedata selection block 154 in FIG. 14 when the selected data is one of thefirst compressed data CDAT1 and the second compressed data CDAT2. Thefirst storage block 172 may output the first previous compressed dataPCDAT1 that was previously stored in the first storage block 172. Asdescribed above with reference to FIGS. 7A, 7B, 11A and 11B, the bitstream of the first compressed data CDAT1 may be similar to the bitstream of the second compressed data CDAT2, and thus both the firstcompressed data CDAT1 and the second compressed data CDAT2 may be usedas the first previous compressed data PCDAT1.

The second storage block 174 may store the selected data output from thedata selection block 154 in FIG. 14 when the selected data is the thirdcompressed data CDAT3. The second storage block 174 may output thesecond previous compressed data PCDAT2 that was previously stored in thesecond storage block 174. As described above with reference to FIGS. 13Aand 13B, the bit stream of the third compressed data CDAT3 may bedifferent from the bit streams of the first and second compressed dataCDAT1 and CDAT2, and thus the third compressed data CDAT3 may be used asthe second previous compressed data PCDAT2 that is distinct from thefirst previous compressed data PCDAT1.

In an exemplary embodiment, each of the first and second storage blocks172 and 174 includes a line memory that stores the compressed data inunits of lines.

As described above with reference FIGS. 1 through 15, in an embodiment,the image encoding device 100 generates 19 bits of the first compresseddata CDAT1, 19 bits of the second compressed data CDAT2 and 19 bits ofthe third compressed data CDAT3 by compressing 96 bits of the seconddata CIMG associated with the current compressing area CAREA, selectsone of the first compressed data CDAT1, the second compressed data CDAT2and the third compressed data CDAT3 as the selected data, and outputscompressed data OCDAT based on the selected data. The selected data mayhave a minimum error with respect to the second data CIMG. Thus, theimage encoding device 100 may compress the second data CIMG with arelatively high compression ratio (e.g., a compression ratio of about1:5). In addition, the image encoding device 100 may have a relativelysmall size, reduced power consumption, and enhanced operation speed.

FIG. 16 is a block diagram illustrating an image encoding deviceaccording to an exemplary embodiment of the inventive concept.

Referring to FIG. 16, an image encoding device 200 includes a firstcompression unit 220, a second compression unit 230, a third compressionunit 240 and an output unit 250. The image encoding device 200 mayfurther include an input buffer unit 210, a pattern decision unit 260and a storage unit 270.

The first compression unit 220 generates the first compressed data CDAT1by averaging and compressing the first data RIMG based on the firstcompression scheme. The first compression unit 220 may further generatethe first error signal ES1 that corresponds to the difference betweenthe second data CIMG and the first compressed data CDAT1. In thisembodiment, the first compression unit 220 may include a first averagingblock, a first mode selection block and a first compression block asillustrated in FIG. 4, and may further include a first error calculationblock that generates the first error signal ES1.

The second compression unit 230 generates the second compressed dataCDAT2 by averaging and compressing the second data CIMG based on thesecond compression scheme, when the current compressing block CAREAcorresponds to the first pattern. The second compression unit 230 mayfurther generate the second error signal ES2 that corresponds to thedifference between the second data CIMG and the second compressed dataCDAT2. In this embodiment, the second compression unit 230 may include asecond averaging block, a second mode selection block and a secondcompression block as illustrated in FIG. 10, and may further include asecond error calculation block that generates the second error signalES2.

The third compression unit 240 generates the third compressed data CDAT3by dividing the current compressing block CAREA into at least twogroups, and by averaging and compressing data corresponding to eachgroup based on the third compression scheme, when the currentcompressing block CAREA corresponds to one of the plurality of secondpatterns. The third compression unit 240 may further generate the thirderror signal ES3 that corresponds to the difference between the seconddata CIMG and the third compressed data CDAT3. In this embodiment, thethird compression unit 240 may include a third averaging block, a thirdmode selection block and a third compression block as illustrated inFIG. 12, and may further include a third error calculation block thatgenerates the third error signal ES3.

The output unit 250 may select one of the first compressed data CDAT1,the second compressed data CDAT2 and the third compressed data CDAT3 asthe selected data, based on the first error signal ES1, the second errorsignal ES2 and the third error signal ES3. The selected data may have aminimum error with respect to the second data CIMG. The output unit 250may output compressed data OCDAT based on the selected data. In anembodiment, the output unit 250 may be implemented without the errorcalculation block, and may include the data selection block and the bitstream generation block as illustrated in FIG. 14.

The input buffer unit 210, the pattern decision unit 260 and the storageunit 270 may be substantially the same as the input buffer unit 110, thepattern decision unit 160 and the storage unit 170 in FIG. 1,respectively.

In an exemplary embodiment, if the current compressing block CAREAcorresponds to the first pattern, the third compressed data CDAT3corresponds to the predetermined null value, and the third error signalES3 corresponding to the third compressed data CDAT3 may have a maximumerror value. In another exemplary embodiment, if the current compressingblock CAREA corresponds to one of the plurality of second patterns, thesecond compressed data CDAT2 and/or the first compressed data CDAT1correspond to the predetermined null value, and the second error signalES2 corresponding to the second compressed data CDAT2 and/or the firsterror signal ES1 corresponding to the first compressed data CDAT1 mayhave a maximum error value.

FIG. 17 is a flow chart illustrating a method of encoding an imageaccording to an exemplary embodiment of the inventive concept.

Referring to FIGS. 1, 2 and 17, in a method of encoding an imageaccording to an exemplary embodiment, the first compressed data CDAT1 isgenerated by compressing the first data RIMG associated with thereference block RAREA based on the first compression scheme (step S110).When the current compressing block CAREA corresponds to the firstpattern, the second compressed data CDAT2 is generated by compressingthe second data CIMG associated with the current compressing block CAREAbased on the second compression scheme (step S120). When the currentcompressing block CAREA corresponds to one of the plurality of secondpatterns, the third compressed data CDAT3 is generated by compressingthe second data CIMG based on the third compression scheme (step S130).The output compressed data OCDAT is generated based on the firstcompressed data CDAT1, the second compressed data CDAT2 and the thirdcompressed data CDAT3 (step S140). The output compressed data OCDATcorresponds to the current compressing block CAREA and the second dataCIMG. For example, the reference block RAREA may be comprised of sixteenunit pixels that are arranged in a 4×4 square matrix formation. Thecurrent compressing block CAREA may be comprised of four unit pixelsthat are arranged in a 2×2 square matrix formation, and may be includedin the reference block RAREA.

FIG. 18 is a flow chart illustrating an exemplary embodiment of stepS110 in FIG. 17.

Referring to FIGS. 1, 2, 3, 4, 17 and 18, during step S110, the firstaverage data ADAT1 may be generated by averaging the plurality of firstpixel values included in the first data RIMG (step S112). The first modeselection signal MS1 may be generated by comparing the first averagedata ADAT1 with the first previous compressed data PCDAT1 (step S114).The first mode selection signal MS1 may indicate a sub-compressionscheme for the first average data ADAT1. The first compressed data CDAT1may be generated by compressing the first average data ADAT1 based onthe first mode selection signal MS1 (step S116).

The first previous compressed data PCDAT1 may be generated bycompressing the plurality of the third pixel values included in thethird data associated with the previous compressing block PCAREA basedon the first compression scheme or the second compression scheme. Thesub-compression scheme for the first average data ADAT1 may include thefirst sub-compression scheme and the second sub-compression scheme. Inthe first sub-compression scheme, the first compressed data CDAT1 may begenerated by calculating a difference between the first average dataADAT1 and the first previous compressed data PCDAT1 and by compressingthe first average data ADAT1 based on the calculated difference. In thesecond sub-compression scheme, the first compressed data CDAT1 may begenerated by truncating a portion of the first average data ADAT1.

FIG. 19 is a flow chart illustrating an exemplary embodiment of stepS120 in FIG. 17.

Referring to FIGS. 1, 2, 3, 10, 17 and 19, during step S120, the secondaverage data ADAT2 may be generated by averaging the plurality of secondpixel values included in the second data CIMG (step S122). The secondmode selection signal MS2 may be generated by comparing the secondaverage data ADAT2 with the first previous compressed data PCDAT1 (stepS124). The second mode selection signal MS2 may indicate asub-compression scheme for the second average data ADAT1. The secondcompressed data CDAT2 may be generated by compressing the second averagedata ADAT2 based on the second mode selection signal MS2 (step S126).The sub-compression scheme for the second average data ADAT2 may includethe first sub-compression scheme and the second sub-compression scheme.

FIG. 20 is a flow chart illustrating an exemplary embodiment of stepS130 in FIG. 17.

Referring to FIGS. 1, 2, 3, 12, 17 and 20, during step S130, the thirdand fourth average data ADAT3 and ADAT4 may be generated based on theplurality of second pixel values included in the second data CIMG (stepS132). The third mode selection signal MS3 may be generated by comparingthe third and fourth average data ADAT3 and ADAT4 with the secondprevious compressed data PCDAT2 (step S134). The third mode selectionsignal MS3 may indicate a sub-compression scheme for the third andfourth average data ADAT3 and ADAT4. The third compressed data CDAT3 maybe generated by compressing the third and fourth average data ADAT3 andADAT4 based on the third mode selection signal MS3 (step S136).

For example, the third average data ADAT3 may be generated by dividingthe plurality of second pixel values included in the second data CIMGinto the first group and the second group, and by averaging the pixelvalues included in the first group. The fourth average data ADAT4 may begenerated by averaging the pixel values included in the second group.The second previous compressed data PCDAT2 may be generated bycompressing the plurality of the third pixel values included in thethird data associated with the previous compressing block PCAREA basedon the third compression scheme. The sub-compression scheme for thethird and fourth average data ADAT3 and ADAT4 may include the firstsub-compression scheme and the second sub-compression scheme.

FIG. 21 is a flow chart illustrating an exemplary embodiment of stepS140 in FIG. 17.

Referring to FIGS. 1, 2, 14, 17 and 21, during step S140, the firsterror signal ES1, the second error signal ES2 and the third error signalES3 may be generated based on the first compressed data CDAT1, thesecond compressed data CDAT2, the third compressed data CDAT3 and thesecond data CIMG (step S142). One of the first compressed data CDAT1,the second compressed data CDAT2 and the third compressed data CDAT3 maybe selected based on the first error signal ES1, the second error signalES2 and the third error signal ES3 (step S144). The selected data mayhave the minimum error with respect to the second data CIMG. The outputcompressed data OCDAT may be generated based on the selected data (stepS146).

The first error signal ES1 may correspond to the difference between thefirst data RIMG and the first compressed data CDAT1. In anotherembodiment, the first error signal ES1 may correspond to the differencebetween the second data CIMG and the first compressed data CDAT1. Thesecond error signal ES2 may correspond to the difference between thesecond data CIMG and the second compressed data CDAT2. The third errorsignal ES3 may correspond to the difference between the second data CIMGand the third compressed data CDAT3.

FIG. 22 is a flow chart illustrating a method of encoding an imageaccording to an exemplary embodiment of the inventive concept.

Referring to FIGS. 1, 2 and 22, in the method of encoding the image, thefirst compressed data CDAT1 is generated by compressing the first dataRIMG associated with the reference block RAREA based on the firstcompression scheme (step S210). It is determined whether the currentcompressing block CAREA corresponds to one of the plurality of patterns(e.g., the plurality of second patterns in FIGS. 8B, 8C, 8D, 8E, 8F, 8G,8H) (step S220). If the current compressing block CAREA does notcorrespond to one of the plurality of patterns, the second compresseddata CDAT2 is generated by compressing the second data CIMG associatedwith the current compressing block CAREA based on the second compressionscheme (step S230), and one of the first compressed data CDAT1 and thesecond compressed data CDAT2 is selected (step S240). The selection maybe made such that the selected data has a minimum error with respect tothe second data CIMG. If the current compressing block CAREA correspondsto one of the plurality of patterns, the third compressed data CDAT3 isgenerated by compressing the second data CIMG based on the thirdcompression scheme (step S250), and one of the first compressed dataCDAT1 and the third compressed data CDAT3 is selected (step S260). Theselection may be made such that the selected data has a minimum errorwith respect to the second data CIMG. The output compressed data OCDATis generated based on the selected data (step S270).

The steps S210, S230 and S250 may be substantially the same as the stepsS110, S120, S130 in FIG. 17, respectively. The steps S240 and S270 maybe similar to the step S140 in FIG. 17. The steps S260 and S270 may alsobe similar to the step S140 in FIG. 17.

FIG. 23 is a flow chart illustrating an exemplary embodiment of stepS220 in FIG. 22.

Referring to FIGS. 1, 2, 9, 22 and 23, during step S220, the pluralityof pixel values included in the second data CIMG are obtained (stepS222). The plurality of parameters PARA01, PARA23, PARA02, PARA13,PARA03 and PARA12 are generated based on the plurality of pixel values(step S224). For example, the plurality of parameters PARA01, PARA23,PARA02, PARA13, PARA03 and PARA12 may be calculated based on theEquations 1, 2, 3, 4, 5 and 6. It is determined whether at least one ofthe plurality of parameters PARA01, PARA23, PARA02, PARA13, PARA03 andPARA12 is larger than the threshold value TH (step S226).

If all of the plurality of parameters PARA01, PARA23, PARA02, PARA13,PARA03 and PARA12 are smaller than the threshold value TH, in otherwords, if the plurality of unit pixels included in the currentcompressing block CAREA have the same or substantially the same pixelvalue, it is determined that the current compressing block CAREA doesnot correspond to one of the plurality of patterns, and then steps S230,S240 and S270 may be performed. If at least one of the plurality ofparameters PARA01, PARA23, PARA02, PARA13, PARA03 and PARA12 is largerthan the threshold value TH, in other words, if some of the plurality ofpixel values included in the second data CIMG are different from theothers of the plurality of pixel values included in the second dataCIMG, it is determined that the current compressing block CAREAcorresponds to one of the plurality of patterns, and then steps S250,S260 and S270 may be performed.

FIG. 24 is a flow chart illustrating a method of encoding an imageaccording to an exemplary embodiment of the inventive concept.

Referring to FIGS. 1, 2 and 24, in the method of encoding the image, itis determined whether the current compressing block CAREA corresponds toone of the plurality of patterns (step S310). If the current compressingblock CAREA does not correspond to one of the plurality of patterns, thefirst compressed data CDAT1 is generated by compressing the first dataRIMG associated with the reference block RAREA based on the firstcompression scheme (step S320), the second compressed data CDAT2 isgenerated by compressing the second data CIMG associated with thecurrent compressing block CAREA based on the second compression scheme(step S330), one of the first compressed data CDAT1 and the secondcompressed data CDAT2 is selected (step S340), and the output compresseddata OCDAT is generated based on the selected data (step S350). Theselection may be made such that the selected data has a minimum errorwith respect to the second data CIMG. If the current compressing blockCAREA corresponds to one of the plurality of patterns, the thirdcompressed data CDAT3 is generated by compressing the second data CIMGbased on the third compression scheme (step S360), and the outputcompressed data OCDAT is generated based on the third compressed dataCDAT3 (step S370).

The step S310 may be substantially the same as the step S220 in FIG. 22.The steps S320, S330 and S360 may be substantially the same as the stepsS110, S120, S130 in FIG. 17, respectively. The steps S340 and S350 maybe similar to the step S140 in FIG. 17.

FIG. 25 is a block diagram illustrating an image decoding deviceaccording to an exemplary embodiment of the inventive concept.

Referring to FIG. 25, an image decoding device 300 includes a modedetermination unit 310, a decompression unit 320 and an imagereconstruction unit 330. The image decoding device 300 may furtherinclude a storage unit 340.

The mode determination unit 310 generates a mode determination signalMDS by determining a compression scheme for input compressed data ICDAT.The input compressed data ICDAT may be provided from the image encodingdevice 100. In an exemplary embodiment, the input compressed data ICDATis a digital bit stream signal that has one of the bit stream structuresillustrated in FIGS. 7A, 7B, 11A, 11B, 13A and 13B.

In an exemplary embodiment, the mode determination unit 310 determinesthe compression scheme for the input compressed data ICDAT by detectingthe upper bits of the input compressed data ICDAT. For example, if theupper one bit of the input compressed data ICDAT corresponds to “0,” itis determined that the input compressed data ICDAT is generated based onthe first compression scheme and the second sub-compression scheme, asdescribed above with reference to FIG. 7A. If the upper four bits of theinput compressed data ICDAT corresponds to “1000,” it is determined thatthe input compressed data ICDAT is generated based on the firstcompression scheme and the first sub-compression scheme, as describedabove with reference to FIG. 7B. If the upper four bits of the inputcompressed data ICDAT corresponds to “1001” or “1010,” it is determinedthat the input compressed data ICDAT is generated based on the secondcompression scheme and the second sub-compression scheme, or based onthe second compression scheme and the first sub-compression scheme, asdescribed above with reference to FIGS. 11A and 11B. If the upper threebits of the input compressed data ICDAT corresponds to “110” or “111,”it is determined that the input compressed data ICDAT is generated basedon the third compression scheme and the second sub-compression scheme,or based on the third compression scheme and the first sub-compressionscheme, as described above with reference to FIGS. 13A and 13B.

The decompression unit 320 generates decompressed data DIMG associatedwith the current compressing block CAREA by decompressing the inputcompressed data ICDAT based on the mode determination signal MDS. Thedecompression unit 320 may include a first decompression unit 322, asecond decompression unit 324 and a third decompression unit 326.

The first decompression unit 322 may generate the decompressed data DIMGbased on a first decompression scheme when the input compressed dataICDAT is generated based on the first compression scheme. The firstdecompression scheme may correspond to the first compression scheme, andthe first compression scheme may indicate that the input compressed dataICDAT is generated by averaging and compressing the first data RIMGassociated with the reference block RAREA. As described above withreference to FIGS. 5 and 6, the first decompression scheme may include afirst sub-decompression scheme corresponding to the firstsub-compression scheme and a second sub-decompression schemecorresponding to the second sub-compression scheme. If the inputcompressed data ICDAT is generated based on the first compression schemeand the first sub-compression scheme, the decompressed data DIMG may begenerated based on the input compressed data ICDAT and previousdecompressed data PDIMG associated with the previous compressing blockPCAREA.

The second decompression unit 324 may generate the decompressed dataDIMG based on a second decompression scheme when the input compresseddata ICDAT is generated based on the second compression scheme. Thesecond decompression scheme may correspond to the second compressionscheme, and the second compression scheme may indicate that the inputcompressed data ICDAT is generated by averaging and compressing thesecond data CIMG associated with the current compressing block CAREA.The second decompression scheme may include the first sub-decompressionscheme and the second sub-decompression scheme.

The third decompression unit 326 may generate the decompressed data DIMGbased on a third decompression scheme when the input compressed dataICDAT is generated based on the third compression scheme. The thirddecompression scheme may correspond to the third compression scheme, andthe third compression scheme may indicate that the input compressed dataICDAT is generated by dividing the current compressing block CAREA intoat least two groups, and by averaging and compressing data correspondingto each group. The third decompression scheme may include the firstsub-decompression scheme and the second sub-decompression scheme.

The image reconstruction unit 330 generates image data OIMG of an outputimage by reconstructing the decompressed data DIMG. The image data OIMGof the output image may correspond to the image data IIMG of the inputimage that is input to the image encoding device 100 of FIG. 1. Forexample, the image data OIMG of the output image may be generated byarranging the previous decompressed data PDIMG and the decompressed dataDIMG in an order of the decompression operation.

The storage unit 340 may store the decompressed data DIMG. The storageunit 340 may output the previous decompressed data PDIMG that waspreviously stored in the storage unit 340. The previous decompresseddata PDIMG may be provided to the decompression unit 320.

In an embodiment, the image decoding device 300 determines thecompression scheme for input compressed data ICDAT based on the upperbits of the input compressed data ICDAT, generates the decompressed dataDIMG based on the decompression scheme corresponding to the determinedcompression scheme, and generates the image data OIMG of the outputimage based on the decompressed data DIMG. Thus, the image decodingdevice 300 is configured to decompress the data compressed by the imageencoding device 100 of FIG. 1. In addition, the image decoding device300 may have a relatively small size, reduced power consumption, andenhanced operation speed.

FIG. 26 is a flow chart illustrating a method of decoding a compressedimage according to an exemplary embodiment of the inventive concept.

Referring to FIGS. 25 and 26, in the method of decoding the compressedimage, the mode determination signal MDS is generated by determining thecompression scheme for the input compressed data ICDAT (step S410). Thedecompressed data DIMG is generated by decompressing the inputcompressed data ICDAT based on the mode determination signal MDS (stepS420). The image data OIMG of the output image is generated byreconstructing the decompressed data DIMG (step S430).

For example, one of the first, second and third compression schemes maybe determined as the compression scheme for input compressed data ICDAT,and the decompressed data DIMG may be generated based on the determinedcompression scheme.

FIG. 27 is a block diagram illustrating an image processing deviceaccording to an exemplary embodiment of the inventive concept.

Referring to FIG. 27, an image processing device 400 includes an imageencoding device 410, a storage device 420, an image decoding device 430and a dynamic capacitance compensation (DCC) circuit 440.

The image encoding device 410 generates a compressed current imageCURR_CDAT by compressing an original current image CURR_IMG. The imageencoding device 410 may be the image encoding device 100 of FIG. 1 orthe image encoding device 200 of FIG. 16, and may include a firstcompression unit 411, a second compression unit 412, a third compressionunit 413 and an output unit (not illustrated). The first compressionunit 411 generates first compressed data by compressing first dataassociated with a first reference block in the original current imageCURR_IMG, based on a first compression scheme. When the firstcompressing block corresponds to a first pattern, the second compressionunit 412 generates second compressed data by compressing second dataassociated with a first compressing block in the original current imageCURR_IMG, based on a second compression scheme. The first compressingblock is included in the first reference block. When the firstcompressing block corresponds to one of a plurality of second patterns,the third compression unit 413 generates third compressed data bycompressing the second data based on a third compression scheme. Theoutput unit generates output compressed data based on the firstcompressed data, the second compressed data and the third compresseddata. The output compressed data corresponds to the second data andcorresponds to a portion of the compressed current image CURR_CDAT. Theimage encoding device 410 may be able to compress the original currentimage CURR_IMG with a relatively high compression ratio, based on threedistinct compression schemes.

The storage device 420 stores the compressed current image CURR_CDAT,and outputs a compressed previous image PREV_CDAT that was previouslystored in the storage device 420. The compressed previous imagePREV_CDAT is generated by compressing an original previous imagepreceding the original current image CURR_IMG. The storage device 420may include a frame memory that stores a compressed image in units offrames.

The image decoding device 430 generates a reconstructed previous imagePREV_RIMG by decompressing the compressed previous image PREV_CDAT. Theimage decoding device 430 may be the image decoding device 300 of FIG.25, and may include a mode determination unit (not illustrated), a firstdecompression unit 431, a second decompression unit 432, a thirddecompression unit 433 and an image reconstruction unit (notillustrated). The mode determination unit may generate a modedetermination signal by determining a compression scheme for fourthcompressed data associated with a second compressing block in theoriginal previous image. The second compressing block in the originalprevious image may correspond to the first compressing block in theoriginal current image CURR_IMG. The decompression units 431, 432 and433 may generate decompressed data by decompressing the fourthcompressed data based on the mode determination signal. The imagereconstruction unit may generate the reconstructed previous imagePREV_RIMG by reconstructing the decompressed data. The first, second andthird decompression units 431, 432 and 433 in the image decoding device430 may correspond to the first, second and third compression units 411,412 and 413 in the image encoding device 410, respectively. The firstdecompression unit 431 may generate the decompressed data based on afirst decompression scheme when the fourth compressed data is generatedby compressing a plurality of pixel values associated with a secondreference block in the original previous image. The second referenceblock in the original previous image may correspond to the firstreference block in the original current image CURR_IMG; and the secondcompressing block may be included in the second reference block. Thesecond decompression unit 432 may generate the decompressed data basedon a second decompression scheme when the fourth compressed data isgenerated by compressing a plurality of pixel values associated with thesecond compressing block in the original previous image. The thirddecompression unit 433 may generate the decompressed data based on athird decompression scheme when the fourth compressed data is generatedby dividing the plurality of pixel values associated with the secondcompressing block into a first group and a second group, by compressingpixel values included in the first group, and by compressing pixelvalues included in the second group. The image decoding device 430 isconfigured to decompress the data compressed by the image encodingdevice 410.

The DCC circuit 440 generates a compensation image COMPEN_IMG based onthe original current image CURR_IMG and the reconstructed previous imagePREV_RIMG.

FIG. 28 is a block diagram illustrating an exemplary embodiment of a DCCcircuit included in the image processing device of FIG. 27.

Referring to FIG. 28, the DCC circuit 440 includes a lookup table 442and a conversion unit 444.

The lookup table 442 may store a plurality of compensation values thatare used to compensate the original current image CURR_IMG. The lookuptable 442 may select at least one of the compensation values based onthe original current image CURR_IMG and the reconstructed previous imagePREV_RIMG to provide the selected compensation value CV to theconversion unit 444.

The conversion unit 444 may selectively compensate the original currentimage CURR_IMG by comparing the original current image CURR_IMG with thereconstructed previous image PREV_RIMG. For example, if a differencebetween the original current image CURR_IMG and the reconstructedprevious image PREV_RIMG is smaller than a compensation reference value,the conversion unit 444 may output the original current image CURR_IMGas the compensation image COMPEN_IMG without any compensation and/orconversion. If the difference between the original current imageCURR_IMG and the reconstructed previous image PREV_RIMG is larger thanthe compensation reference value, the conversion unit 444 may generatethe compensation image COMPEN_IMG by compensating the original currentimage CURR_IMG based on the selected compensation value CV.

The image processing device 400 according to an exemplary embodiment ofthe inventive concept includes the image encoding device 410 and theimage decoding device 430. The device 400 may have a relatively smallsize and a relatively high compression/decompression ratio, therebyreducing the size of the storage device 420. The image processing device400 generates the compensation image COMPEN_IMG, and thus a responsespeed of a display device driven by the image processing device 400 maybe enhanced, and a defect, such as a flicker noise, on the displaydevice may be reduced. Accordingly, the image processing device 400 maybe employed in an image display system that includes a large displaydevice and/or a high frequency display device.

FIG. 29 is a block diagram illustrating an image processing deviceaccording to an exemplary embodiment of the inventive concept.

Referring to FIG. 29, an image processing device 500 includes an imageencoding/decoding device 510, a storage device 520, an image decodingdevice 530, a DCC input control circuit 540 and a DCC circuit 550.

The image encoding/decoding device 510 generates a compressed currentimage CURR_CDAT by compressing an original current image CURR_IMG, andgenerates a reconstructed current image CURR_RIMG by decompressing thecompressed current image CURR_CDAT. The image encoding/decoding device510 may be implemented with an image encoding device and an imagedecoding device. The image encoding device may be the image encodingdevice 100 of FIG. 1 or the image encoding device 200 of FIG. 16, andmay include a first compression unit 511, a second compression unit 512,a third compression unit 513 and an output unit (not illustrated). Theimage decoding device may be the image decoding device 300 of FIG. 25,and may include a mode determination unit (not illustrated), a firstdecompression unit 514, a second decompression unit 515, a thirddecompression unit 516 and an image reconstruction unit (notillustrated). The image encoding/decoding device 510 may be configuredto compress the original current image CURR_IMG with a relatively highcompression ratio, based on three distinct compression schemes, anddecompress the compressed current image CURR_CDAT.

The storage device 520 stores the compressed current image CURR_CDAT,and outputs a compressed previous image PREV_CDAT that was previouslystored in the storage device 520.

The image decoding device 530 generates a reconstructed previous imagePREV_RIMG by decompressing the compressed previous image PREV_CDAT. Theimage decoding device 530 may be the image decoding device 300 of FIG.25, and may include a mode determination unit (not illustrated), a firstdecompression unit 531, a second decompression unit 532, a thirddecompression unit 533 and an image reconstruction unit (notillustrated). The image decoding device 530 may decompress the datacompressed by the image encoding/decoding device 510.

In an embodiment, the DCC input control circuit 540 determines whetherthe original current image CURR_IMG is a still image or a moving imagebased on the reconstructed previous image PREV_RIMG and thereconstructed current image CURR_RIMG, and outputs one of the originalcurrent image CURR_IMG and the reconstructed previous image PREV_RIMG asa selected image SEL_IMG based on a result of the determination.

FIG. 30 is a block diagram illustrating an exemplary embodiment of a DCCinput control circuit included in the image processing device of FIG.29.

Referring to FIG. 30, the DCC input control circuit 540 includes aregister unit 541, a still image judgment unit 542, a moving vectordetermination unit 543, a matching judgment unit 544, an errorcorreaction unit 545, a reference value determination unit 546 and aprevious image selection unit 547.

The register unit 541 may store at least one image that corresponds to amotion estimation range of a compressing block, among the originalcurrent image CURR_IMG, the reconstructed previous image PREV_RIMG andthe reconstructed current image CURR_RIMG.

In an embodiment, the still image judgment unit 542 generates a firstjudgment signal JS1 based on the reconstructed previous image PREV_RIMGand the reconstructed current image CURR_RIMG. The first judgment signalJS1 may indicate whether the original current image CURR_IMG is a stillimage or a moving image.

The moving vector determination unit 543 may determine a motion vectorMV based on a first image that is one of the reconstructed previousimage PREV_RIMG and the original current image CURR_IMG and correspondsto the motion estimation range of the compressing block.

The matching judgment unit 544 may generate a second judgment signal JS2by determining the matching of the motion vector MV based on a referencevalue RV. For example, the matching judgment unit 544 may compare themotion vector MV with the reference value RV and the second judgmentsignal JS2 may be a result of the comparison.

The error correction unit 545 may generate a correction signal CS bydetermining whether the currently determined motion vector MV isconsistent with a previously determined motion vector, and bydetermining whether the currently determined motion vector MV isconsistent with peripheral motion vectors. For example, if the currentlymotion vector MV is the same as or only differs from the previous motionvector by a small threshold amount, they may be considered consistentwith one another.

In an embodiment, the reference value determination unit 546 isconfigured to determine the reference value RV.

The previous image selection unit 547 may output one of the originalcurrent image CURR_IMG and the reconstructed previous image PREV_RIMG asthe selected image SEL_IMG based on the first judgment signal JS1, thesecond judgment signal JS2 and the correction signal CS.

If it is determined that data included in the original current imageCURR_IMG is not substantially the same as data included in thereconstructed previous image PREV_RIMG, the DCC input control circuit540 outputs the reconstructed previous image PREV_RIMG as the selectedimage SEL_IMG. If it is determined that the data included in theoriginal current image CURR_IMG is substantially the same as the dataincluded in the reconstructed previous image PREV_RIMG, the DCC inputcontrol circuit 540 outputs the original current image CURR_IMG as theselected image SEL_IMG.

Referring back to FIG. 29, the DCC circuit 550 generates a compensationimage COMPEN_IMG based on the original current image CURR_IMG and theselected image SEL_IMG.

The image processing device 500 according to an exemplary embodiment ofthe inventive concept includes the image encoding/decoding device 510and the image decoding device 530. The device 500 may have a relativelysmall size and a relatively high compression/decompression ratio,thereby reducing the size of the storage device 520. The imageprocessing device 500 generates the compensation image COMPEN_IMG, andthus a response speed of a display device driven by the image processingdevice 500 may be enhanced, and a defect, such as a flicker noise, onthe display device may be reduced. Accordingly, the image processingdevice 500 may be employed in an image display system that includes alarge display device and/or a high frequency display device.

FIG. 31 is a block diagram illustrating a display system according to anexemplary embodiment of the inventive concept.

Referring to FIG. 31, a display system 600 includes an image providingdevice 610, an image processing device 620 and a display device 630.

The image providing device 610 provides image (e.g., an image includingRGB data) to the image processing device 620. For example, the imageproviding device 610 may provide at least one of various sources ofimage, such as image receiver of a digital TV (e.g., a set-top box), acomputer, etc.

The image processing device 620 compensates the image received from theimage providing device 610 to generate a compensation image. The imageis displayed on the display device 630 based on the compensation imagereceived from the image processing device 620.

The image processing device 620 may be the image processing device 400of FIG. 27 or the image processing device 500 of FIG. 29, and mayinclude an image encoding device 622 and an image decoding device 624.The image encoding device 622 may compress the image with a relativelyhigh compression ratio, based on three distinct compression schemes. Theimage decoding device 624 may decompress the data compressed by theimage encoding device 622. Thus, the display device 630 may haveenhanced response speed and may provide a high quality image.

According to an exemplary embodiment of the inventive concept, thedisplay device 630 includes at least one of various display panels, suchas a cathode ray tube (CRT) panel, a plasma display panel (PDP), a lightemitting diode (LED) display panel, an organic LED (OLED) display panel,a field emission display (FED) panel, etc.

At least one of the above described embodiments may be applied to asystem including an image processing device performing imagecompression/decompression operations and the display device. Forexample, at least one of the above described embodiments may be appliedto various electronic devices, such as a memory card, a solid statedrive, a desktop computer, a laptop computer, a tablet computer, amobile phone, a smart phone, a music player, a personal digitalassistant PDA, a personal media player PMP, a digital television, adigital camera, a portable game console, etc.

The foregoing is illustrative of example embodiments and is not to beconstrued as limiting thereof. Although exemplary embodiments have beendescribed, many modifications are possible in these exemplaryembodiments without materially departing from the present inventiveconcept. Accordingly, all such modifications are intended to be includedwithin the scope of the present inventive concept.

What is claimed is:
 1. An image encoding device, comprising: a firstcompression unit configured to generate first compressed data bycompressing first data associated with a reference block in an inputimage; a second compression unit configured to generate secondcompressed data by compressing second data associated with a currentcompressing block in the input image when the current compressing blockcorresponds to a first pattern, wherein the current compressing block isincluded in the reference block; a third compression unit configured togenerate third compressed data by compressing the second data when thecurrent compressing block corresponds to one of a plurality of secondpatterns; and an output unit configured to output compressed data basedon the first compressed data, the second compressed data and the thirdcompressed data.
 2. The image encoding device of claim 1, wherein thesecond compression unit generates the second compressed data if adifference between a first pixel value of the second data and a secondpixel value of the second data is smaller than a threshold value.
 3. Theimage encoding device of claim 2, wherein the third compression unitgenerates the third compressed data if the difference between the firstpixel value and the second pixel value is equal to or larger than thethreshold value.
 4. The image encoding device of claim 1, wherein theoutput unit selects one of the first compressed data, the secondcompressed data and the third compressed data as selected data, andoutputs the compressed data based on the selected data.
 5. The imageencoding device of claim 4, wherein the selected data is one of thefirst compressed data and the second compressed data when the currentcompressing block corresponds to the first pattern, and wherein theselected data is the third compressed data when the current compressingblock corresponds to one of the plurality of second patterns.
 6. Theimage encoding device of claim 1, wherein the first data include aplurality of first pixel values and the second data include a pluralityof second pixel values, and wherein the first compression unitcomprises: a first averaging block configured to generate first averagedata by averaging the plurality of first pixel values; a first modeselection block configured to generate a first mode selection signal bycomparing the first average data with first previous compressed data,wherein the first mode selection signal indicates a compression schemefor the first average data, wherein the first previous compressed datais generated by compressing third data associated with a previouscompressing block in the input image, and wherein the previouscompressing block is adjacent the current compressing block; and a firstcompression block configured to generate the first compressed data bycompressing the first average data based on the first mode selectionsignal.
 7. The image encoding device of claim 6, wherein the firstcompressed data is generated based on a differential pulse codemodulation (DPCM) scheme that calculates a difference between the firstaverage data and the first previous compressed data and compresses thefirst average data based on the calculated difference if the first modeselection signal has a first logic level, and wherein the firstcompressed data is generated based on a pulse code modulation (PCM)scheme that truncates a portion of the first average data if the firstmode selection signal has a second logic level.
 8. The image encodingdevice of claim 6, wherein the second compression unit comprises: asecond averaging block configured to generate second average data byaveraging the plurality of second pixel values; a second mode selectionblock configured to generate a second mode selection signal by comparingthe second average data with the first previous compressed data, whereinthe second mode selection signal indicates a compression scheme for thesecond average data; and a second compression block configured togenerate the second compressed data by compressing the second averagedata based on the second mode selection signal.
 9. The image encodingdevice of claim 8, wherein the third compression unit comprises: a thirdaveraging block configured to divide the plurality of second pixelvalues into a first group and a second group, configured to generatethird average data by averaging pixel values included in the firstgroup, and configured to generate fourth average data by averaging pixelvalues included in the second group; a third mode selection blockconfigured to generate a third mode selection signal by comparing thethird and fourth average data with second previous compressed data,wherein the third mode selection signal indicates a compression schemefor the third and fourth average data, and wherein the second previouscompressed data is generated by compressing the third data in a mannerdistinct from the first previous compressed data; and a thirdcompression block configured to generate the third compressed data bycompressing the third and fourth average data based on the third modeselection signal.
 10. The image encoding device of claim 9, furthercomprising: a storage unit configured to store one of the firstcompressed data, the second compressed data and the third compresseddata, and configured to output the first previous compressed data andthe second previous compressed data that were previously stored in thestorage unit.
 11. The image encoding device of claim 1, furthercomprising: a pattern decision unit configured to compare a first pixelvalue with a second pixel value to generate comparison results andconfigured to generate a pattern decision signal based on the comparisonresults, wherein the second data associated with the current compressingblock includes a plurality of pixel values, wherein each of the firstand second pixel values is one of the plurality of pixel values, andwherein the pattern decision signal indicates whether the currentcompressing block corresponds to the first pattern or one of theplurality of second patterns.
 12. An image processing device,comprising: an image encoding device configured to generate a compressedcurrent image by compressing an original current image; a storage deviceconfigured to store the compressed current image, and configured tooutput a compressed previous image that was previously stored in thestorage device, wherein the compressed previous image is generated bycompressing an original previous image preceding the original currentimage; an image decoding device configured to generate a reconstructedprevious image by decompressing the compressed previous image; and adynamic capacitance compensation (DCC) circuit configured to generate acompensation image based on the original current image and thereconstructed previous image, and wherein the image encoding device,comprises: a first compression unit configured to generate firstcompressed data by compressing first data associated with a firstreference block in the original current image; a second compression unitconfigured to generate second compressed data by compressing second dataassociated with a first compressing block in the original current imagewhen the first compressing block corresponds to a first pattern, whereinthe first compressing block is included in the first reference block; athird compression unit configured to generate third compressed data bycompressing the second data when the first compressing block correspondsto one of a plurality of second patterns; and an output unit configuredto output compressed data based on the first compressed data, the secondcompressed data and the third compressed data, the output compresseddata corresponding to the first compressing block and corresponding to aportion of the compressed current image.
 13. The image processing deviceof claim 12, further comprising: a DCC input control circuit configuredto determine whether the original current image is a still image or amoving image based on the reconstructed previous image and areconstructed current image, and configured to output one of theoriginal current image and the reconstructed previous image as aselected image based on a result of the determination, wherein thereconstructed current image is generated by decompressing the compressedcurrent image, wherein the DCC circuit generates the compensation imagebased on the original current image and the selected image.
 14. Theimage processing device of claim 12, wherein the image decoding devicecomprises: a mode determination unit configured to generate a modedetermination signal by determining a compression scheme for fourthcompressed data associated with a second compressing block in theoriginal previous image, wherein the second compressing blockcorresponds to the first compressing block in the original currentimage; a decompression unit configured to generate decompressed data bydecompressing the fourth compressed data based on the mode determinationsignal; and an image reconstruction unit configured to generate thereconstructed previous image by reconstructing the decompressed data.15. The image processing device of claim 14, wherein the decompressionunit includes: a first decompression unit configured to generate thedecompressed data based on a first decompression scheme when the fourthcompressed data is generated by compressing a plurality of first pixelvalues associated with a second reference block in the original previousimage, the second reference block corresponding to the first referenceblock in the original current image, and wherein the second compressingblock is included in the second reference block; a second decompressionunit configured to generate the decompressed data based on a seconddecompression scheme when the fourth compressed data is generated bycompressing a plurality of second pixel values associated with thesecond compressing block; and a third decompression unit configured togenerate the decompressed data based on a third decompression schemewhen the fourth compressed data is generated by dividing the pluralityof second pixel values into a first group and a second group, bycompressing pixel values included in the first group, and by compressingpixel values included in the second group.
 16. A compression system,comprising: a first compression unit configured to generate firstcompressed data by compressing first average data that is an average ofpixel values of a part of an input image; a second compression unitconfigured to generate second compressed data by compressing secondaverage data that is an average of pixel values of a sub-part within thepart smaller than the part when the sub-part is one pattern; a thirdcompression unit configured to generate third compressed data bycompressing third and fourth average data when the sub-part is a secondother pattern, wherein the third average data is an average of some ofthe pixel values and the fourth average data is an average of theremaining pixel values; and an output unit configured to outputcompressed data by selecting one of the first, second, and thirdcompressed data.
 17. The compression system of claim 16, wherein thefirst compression unit is configured to output an error signal based ona difference between the sub-part and the first compressed data, whereinthe second compression units is configured to output an error signalbased on a difference between the sub-part and the second compresseddata, and the third compression unit is configured to output an errorsignal based on a difference between the sub-part and the thirdcompressed data.
 18. The compression system of claim 16, wherein eachcompression unit compresses average data input thereto based on adifferential pulse code modulation (DPCM) scheme when previouslycompressed data is available and based on a PCM scheme otherwise. 19.The compression system of claim 17, wherein when the sub-part is not theone pattern, the second compression unit disables compression withinitself.
 20. The compression system of claim 17, wherein when thesub-part is not the other pattern, the third compression unit disablescompression within itself.